This invention relates to a constant flow control valve by which flow range can be simply varied.
In a generally known constant flow control valve an orifice is opposed concentrically to a needle in a conduit of a main body, whereby a valve opening is formed. Either one of the orifice and the needle is fixed, the other one being supported resiliently and movably by a coil spring or the like.
By balancing the coil spring with a fluid dynamic pressure acting thereon, it is possible to obtain a constant flow rate by varying the area of the valve opening in a form of inverse function.
In such a conventional constant flow control valve, in order to obtain a constant flow control valve permitting any desired flow rate, it is necessary to replace an orifice or a needle forming a valve opening or a coil spring, etc. with other suitable ones in accordance with respective preset flow rate.
Accordingly, users are obliged to prepare various kinds of orifices, needles and coil springs in accordance with the preset flow rate. This is one of the main disadvantages of the conventional constant flow control valve in that a constant flow control valve capable of varying flow range easily cannot be obtained economically.